Method for constructing a building using bricks connected using dry joints

ABSTRACT

The invention relates to a brick ( 1 ) made from a material comprising vegetable fibres agglomerated using a binder (such as hemp concrete), said brick being provided with a groove ( 9, 11 ) and a tongue ( 5, 7 ) allowing the dry-joint connection of bricks. The invention also relates to a method for constructing a building using such bricks.

TECHNICAL FIELD

The invention relates to the field of construction. More specifically, it relates to a method for making a building from prefabricated and interlocking elementary bricks, made from a material comprising plant fibers (hemp, straw, flax, etc.) agglomerated using a binder (in particular dirt, non-hydraulic or hydraulic lime).

BRIEF DESCRIPTION OF RELATED ART

The use of plant fibers to construct buildings, and more specifically to produce walls and partitions, has been known for some time. Examples include laterite mud, made up of a matrix of clay (or more generally dirt) and agglomerated plant fibers (in particular straw).

Hemp fibers have also been used in construction. One traditional technique consists of preparing a concrete (commonly, although wrongly, called hemp “concrete”) in situ from a plant aggregate (hemp chaff) and a binder (non-hydraulic or hydraulic lime), and filling a wooden framework wall using such a concrete.

Hemp concrete may also be used to produce concrete slabs, insulating coats, or insulation per se, which is for example poured into the rakes of a roof before placing a cover.

A number of recipes and applications exist for hemp concrete. The Association Construire en Chanvre specifically defined hemp concrete and formulated professional rules for building with hemp concrete. These rules were published in a volume entitled Construire en Chanvre (ISBN 978-2-915162-92-9). For an exhaustive list of works, articles and publications relative to hemp-based construction, see the bibliography published on the Association's website: http://www.construction-chanvre.asso.fr/.

While the ordinary techniques, today offered by several companies (including the company BCB, which offers hemp concrete under the Tradical registered trademark), may be deemed satisfactory in terms of mechanical, acoustic and thermal performance (greater than or equal to that of ordinary quarry stone constructions), they are nevertheless flawed by a high degree of technicality and difficult implementation, which limit their use to building professionals.

Techniques have been proposed to resolve these drawbacks and democratize the use of hemp in construction. One of these techniques, described in French patent application FR 2 871 487 in the name of the company Développement Construction Ecologique (see also the American equivalent US 2008/272270), consists of making a wall from prefabricated blocks that are assembled in situ. These blocks are provided with vertical shafts in which wooden posts are inserted to form a framework. The shafts are then sealed in the blocks using a filler, such as a binder of the lime milk type.

It is true that the use of prefabricated blocks makes it possible to save on the on-site preparation of the hemp concrete. However, the savings are marginal, since the insertion, then sealing of many posts in the shafts of the blocks are lengthy and tedious operations, which also require the in situ preparation of a large quantity of binder.

Due to the aforementioned drawbacks of the known techniques, including the most recent, the share of hemp concrete in construction is progressing little if at all, traditional quarry stone construction continuing to represent the vast majority of the market.

BRIEF SUMMARY

The invention aims to improve the use of plant fibers (in particular hemp) in construction, by proposing an implementation that is both simple and fast, capable of equaling or even surpassing the ordinary construction techniques (in particular terra cotta bricks or cement concrete quarry stone).

To that end, the invention first proposes a method for constructing a building using prefabricated bricks made from a material (such as hemp concrete) comprising plant fibers agglomerated using a binder, provided with grooves and tongues allowing the dry-joint connection thereof.

According to one embodiment, this method comprises the combined placement of solid base bricks, provided with a groove and a tongue that can be joined together, and honeycomb stiffening bricks, provided with a groove and a tongue, that can be joined together as well as a cell with the passage of a reinforcing post.

The following operations may be provided:

-   -   producing a mortar base;     -   placing a series of posts in the base;     -   placing stiffening bricks at the posts, with insertions of said         posts into the cells of the stiffening bricks;     -   placing base bricks between the stiffening bricks.

Each post for example comprises a metal framework embedded in (cement) concrete.

It is also possible to provide an operation for placing, at a post and above the stiffening brick, a half-stiffening brick, provided with a tongue to allow it to be joint-connected on the stiffening brick and a cell for the passage of the post, and having a length equal to half the length of the stiffening brick.

The following operations may also be provided:

-   -   placing linking bricks comprising a tongue allowing them to be         joint-connected in the grooves of other bricks, and a central         cavity delimiting two side walls and a bottom;     -   placing a metal framework in the cavity;     -   filling in the cavity using concrete.

Likewise, the following operations may be provided:

-   -   placing linking bricks comprising a tongue allowing them to be         joint-connected in the grooves of other bricks, and a central         cavity delimiting two side walls and a bottom;     -   cutting out side walls;     -   placing a slab resting directly on the bottom of the linking         bricks.

The invention secondly proposes, for the implementation of the aforementioned method, a hemp concrete brick, provided with a tongue designed to be joint-connected in a groove, said tongue having a protrusion whereof the ratio to an effective height or effective width of the brick is comprised between 1/10 and 1/4, preferably approximately 1/5.

According to one embodiment, the tongue also has a width whereof the ratio to an effective width of the brick is comprised between 1/4 and 1/2, preferably approximately equal to 1/3.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aims of advantages of the invention will appear in light of the following description, done in reference to the appended drawings, in which:

FIG. 1 is a perspective view of a first type of hemp concrete brick;

FIG. 2 is a side view of the brick of FIG. 1;

FIG. 3 is a top view of the brick of FIG. 1;

FIG. 4 is a perspective view of a second type of hemp concrete brick;

FIG. 5 is a side view of the brick of FIG. 4;

FIG. 6 is a top view of the brick of FIG. 4;

FIG. 7 is a perspective view of a third type of hemp concrete brick;

FIG. 8 is a side view of the brick of FIG. 7;

FIG. 9 is a top view of the brick of FIG. 7;

FIG. 10 is a perspective view of a fourth type of hemp concrete brick;

FIG. 11 is a side view of the brick of FIG. 10;

FIG. 12 is a top view of the brick of FIG. 10;

FIGS. 13 to 19 are perspective views showing different successive steps for producing a building from the bricks of FIGS. 1 to 12;

FIGS. 20 and 21 are perspective views showing two successive steps for producing a corner wall from the bricks of FIGS. 1 to 9.

DETAILED DESCRIPTION

FIGS. 1 to 12 show four different types of prefabricated hemp concrete elementary bricks. The concrete is prepared from hemp or hemp chaff aggregate, which is the fragmented inner part of the hemp stalk. The hemp chaff used meets the recommendations of hemp producers for use in construction, cf. the aforementioned volume Construire en Chanvre. The density of the dry hemp chaff used is approximately 100 kg/m³ bulked (i.e. not tamped). The binder used may comprise non-hydraulic or hydraulic lime (standard NF EN 459-1 to 3), potentially with added pozzolana (standard NF P 18-308), but in the case at hand is preferable to use pure non-hydraulic lime. The composition also comprises quick-setting cement and mixing water (meeting the stipulations of standard NF EN 1008).

The proportions by volume of the preferred composition are as follows: hemp chaff 73%; non-hydraulic lime 8%; quick-setting cement 4%; water 15%, i.e., for 100 l (10 kg) of hemp chaff, approximately 11 l of non-hydraulic lime, 5.5 l of quick setting cement and 20 l of water.

After mixing and stirring of the composition, each type of brick is made by pressurized molding (the pressure is done by compaction of the still-wet composition). Once folded, each brick is stripped, then undergoes air drying for several weeks, or may be placed in a drying oven for accelerated drying.

A first type of brick 1 is illustrated in FIGS. 1 to 3. This brick 1, called a base brick, is solid. It has an effective length 2 of 600 mm, an effective width 3 of 300 mm, and an effective height 4 of 300 mm.

The base brick 1 comprises:

-   -   a lower tongue 5 protruding on a lower surface 6;     -   a front tongue 7 protruding on a front surface 8,     -   an upper central groove 9 hollowed in an upper surface 10 of the         brick 1 and that runs over the entire length thereof, including         on the front tongue 7;     -   a rear groove 11 hollowed in a rear surface 12 of the brick 1         and that runs over the entire height thereof, including over the         lower tongue 5.

The tongues 5, 7 have a (protruding) height 13 of 50 mm and a width 14 of 100 mm. The grooves 9, 10 have a depth 13 of 50 mm and a width 14 of 100 mm.

A second type of brick 15 is illustrated in FIGS. 4 to 6. This brick 15, called a stiffener, has a cellular structure. Like the base brick 1, it has an effective length 2 of 600 mm, an effective width 3 of 300 mm, and an effective height 4 of 300 mm.

The stiffener 15 comprises a cell 16 with a square section pierced over the entire height thereof, the sides of which measure 150 mm and are spaced apart from the side 17 and rear 18 surfaces of the stiffener 15 by 75 mm.

The stiffener 15 comprises:

-   -   A lower tongue 19 protruding on a lower surface 20, which is         interrupted at the boundary of the cell 16 (cf. FIG. 5);     -   A front groove 21 hollowed in a front surface 22, which runs         over the entire height of the brick 15, including over the lower         tongue 19;     -   An upper central groove 23 hollowed in an upper surface 24 of         the brick 15 and which extends forward as far as the front         groove 21 and is interrupted toward the back at a distance of 75         mm from the cell 16.

The lower tongue 19 has a protruding height 13 of 50 mm and a width 14 of 100 mm; the grooves 21, 23 have a depth 13 of 50 mm and a width 14 of 100 mm.

A third type of brick 25 is illustrated in FIGS. 7 to 9. This brick 25, called a half-stiffener, has a cellular structure. It has a generally cubic shape with an equal effective length 26, width 3 and height 4 of 300 mm. In this way, the effective length 26 of the half-stiffener 25 is equal to half the effective length 2 of the base brick 1 and the stiffener 15. The half-stiffener 25 comprises a cell 16 with a square section pierced over the entire height thereof, the sides of which measure 150 mm and are spaced apart from the four side surfaces of the half-stiffener 25 by an equal distance of 75 mm. The half-stiffener 25 comprises:

-   -   a front tongue 27 protruding on a front surface 28, which is         interrupted toward the top at a distance of 50 mm from an upper         surface 29 of the brick 25, and is extended downward beyond a         lower surface 30 of the brick 25 over a distance of 50 mm;     -   a central lower tongue 31, which protrudes over the lower         surface 30 of the brick 25, is interrupted toward the rear at         the boundary of the cell 16, and extends forward beyond the         front surface 28 to form a block with an L-shaped profile with         the front tongue 27.

The tongues 27, 31 have a protruding height 13 of 50 mm and a width 14 of 100 mm.

A fourth type of brick 32 is illustrated in FIGS. 10 to 12. This brick 32, called a linking brick, is hollow and has a U-shaped profile in transverse section. It has an effective length 2 of 600 mm, an effective width 3 of 300 mm, and an effective height 4 of 300 mm. These sides are identical to those of the base brick 1 and those of the stiffener 15.

The linking brick 32 comprises:

-   -   a central cavity 33, hollowed out over the entire length of the         brick 32, over a height 34 of 200 mm from an upper surface 35,         and over a width 36 of 150 mm, the central cavity 33 thus         delimiting two sidewalls 37 with a same thickness (75 mm) spaced         apart from the width 36 of the cavity 33, and a bottom 38 with a         thickness of 100 mm;     -   a central lower tongue 39, which protrudes over a lower surface         40 of the brick, is interrupted toward the back at a distance of         50 mm from a rear surface 41 of the brick 32, and extends toward         the front beyond a front surface 42 of the brick 32, over a         distance of 50 mm;     -   a front tongue 43 that protrudes from the front surface 42 of         the brick 32 in the extension of the lower tongue 39 and is         interrupted toward the top at the central cavity 33;     -   a rear groove 44 hollowed in the bottom 38, and which extends         over the height of the lower tongue 39.

The tongues 39, 43 have a protruding height 13 of 50 mm and a width 14 of 100 mm.

The four types of prefabricated elementary bricks that have just been described make it possible to produce any masonry construction, and in particular to build walls and partitions.

To that end, the bricks 1, 15, 25, 32 may be combined with each other. They are in fact designed to fit together both horizontally and vertically. Thus:

-   -   the lower tongue 5 of each base brick 1 may fit into the upper         groove 9 of another base brick 1, in the upper groove 23 of a         stiffener 15, or in the cavity 33 of the linking brick 32 (the         difference in width being able to be filled in with concrete);     -   the front tongue 7 of each base brick 1 can fit into the rear         groove 11 of another base brick 1, in the front groove 21 of a         stiffener 15, or in the rear groove 44 of a linking brick 32;     -   the lower tongue 19 of the stiffener 15 can fit into the upper         groove 9 of the base brick 1, in the upper groove 23 of another         stiffener 15, or in the cavity 33 of a linking brick 32 (the         difference in width being able to be filled in with concrete);     -   the lower tongue 31 of a half-stiffener 25 can fit into the         upper groove 9 of the base brick 1, in the upper groove 23 of         another stiffener 15, or in the cavity 33 of a linking brick 32         (the difference in width being able to be filled in with         concrete;     -   the front tongue 27 of a half-stiffener 25 can fit into the rear         groove 11 of the base brick 1, in the front groove 21 of the         stiffener 15, or in the rear groove 44 of a linking brick 32;     -   the lower tongue 39 of a linking brick 32 can fit into the upper         groove 9 of the base brick 1, in the upper groove 23 of a         stiffener 15, or in the cavity 33 of another linking brick 32         (the difference in width being able to be filled in with         concrete, as will be illustrated hereafter);     -   the front tongue 43 of a linking brick 32 may fit into the rear         groove 44 of another linking brick 32, in the rear groove 11 of         the base brick 1, or in the front groove 21 of the stiffener 15.

As will be seen below, these fittings may be done as dry-joint connections (i.e. without jointing mortar), without harming the stability of the construction one wishes to make, owing to the size ratios between the sides (height and width) of the grooves and tongues, and the effective size ratios of the bricks.

In this way, the ratio between the width 14 of the tongues 5, 7, 19, 27, 31, 39, 43 (equal to that of the grooves 9, 10, 21, 23, 44) and the effective width 3 of the bricks 1, 15, 25, 32 is preferably comprised between 1/4 and 1/2. A ratio of approximately 1/3, which corresponds to the quoted values provided above, is a good compromise between good shearing strength of the tongues 5, 7, 19, 27, 31, 39, 43, which guarantees good strengths of the walls with respect to forces in the orthogonal direction (in particular wind and bearing forces) on the one hand, and a sufficient bearing surface of the bricks 1, 15, 25, 32 on one another, on either side of the tongues 5, 7, 19, 27, 31, 39, 43, guaranteeing good stability of the walls, on the other hand.

Furthermore, the ratio between the height of the tongues 5, 7, 19, 27, 31, 39, 43 (equal to the depth of the grooves 9, 10, 21, 23, 44) and the effective height (or the effective width, equal to the effective height) of the bricks 1, 15, 25, 32 is preferably comprised between 1/10 and 1/4. A ratio of approximately 1/6, which corresponds to the quoted values provided above, is a good compromise between a certain ease of assembly on the one hand, and the need to maximize the contact surfaces between the bricks 1, 15, 25, 32 (i.e. the friction therebetween), so as to stiffen the structure, on the other hand.

FIGS. 13 to 19 show different successive steps in the construction of a structure comprising a straight wall 45, provided with an opening 46 (in this case a window) and topped by a slab 47.

The wall 45 is built on a base 48 (forming a compression slab) made from water-repellent cement mortar, which is poured on a concrete foundation 49 situated below ground level as defined by a finished (i.e. tamped) outside terrain 50. As shown in FIG. 13, the base 48 is partially buried in the ground 50, and has a protruding upper portion in which a groove 51 is followed with a width and depth respectively equal to the width and the depth of the grooves of the bricks. Thus, in this case, the groove 51 has a width of 100 mm and a depth of 50 mm.

In anticipation of the production of the opening 46 on the one hand, and to consolidate the wall 45 on the other hand, two metal frameworks 52 with a square section are vertically implanted in the base 48 for the subsequent production of reinforcing posts 53, while being spaced apart by a predefined value corresponding to three brick lengths (i.e. 1800 mm), this measurement being done on the central axis of the frameworks 52. The frameworks 52 are preferably pre-positioned during pouring of the base 48, so as to be embedded therein, but it is also possible to consider making the base 48 first, then later drilling housings as a function of the desired positioning of the frameworks 52, in the scenario where that positioning is not known when the base 48 is poured.

The wall 45 is then erected through the successive stacking of rows of bricks fitted into each other both horizontally and vertically. FIG. 13 illustrates the placement of a first row of bricks, the lower tongues of which are fitted into the groove 51 of the base 48. This first row alternates between base bricks 1, fitted into the base 48 at locations with no frameworks 52, and stiffeners 15 fitted into the base 48 at the frameworks 52. More specifically, as shown in FIG. 13, the stiffeners 15 are positioned such that the frameworks 52 extend through their cells 16. From a practical perspective, in the case where the frameworks 52 are pre-positioned in the base 48, the stiffeners 15 are simply slipped through the top on the frameworks 52, to then fit into the groove 51 of the base 48.

The base bricks 1 are all oriented in the same direction (their rear surface 12 here turned toward the back in FIG. 13). The stiffeners 15 are also oriented in the same direction, but opposite the base bricks 1. In this way, each stiffener 15 is framed by two base bricks 1: a first whereof the rear surface 12 is simply pressed against the rear surface 18 of the stiffener 15, and a second whereof the front tab 7 is fitted into the front groove 21 of the stiffener 15.

This first row is placed dry, without mortar joints, by simple fitting of the bricks 1, 15 into the base 48. Given the identical quoted values (for the height and width) of the groove 51 of the base 48 and the tongues 5, 7, 19 of the bricks 1, 15, there is no functional play between the groove 51 and the tongues 5, 7, 19. This lack of play does not, however, prevent the fitting, due to the relative elasticity of the material of the bricks 1, 15 (unlike cement concrete, for example, which is extremely rigid).

Before placing the second row of bricks, the following two operations are carried out:

-   -   filling in, preferably using hemp concrete, a gap 54 existing         between the rear surface 18 of each stiffener 15 and the rear         groove 11 of the adjacent base bricks 1;     -   producing a cutout 55 in the front surface 24 of each stiffener         15, on the side of its rear surface 18, to extend the upper         groove 9 of the adjacent base bricks 1 as far as the cells 16         and thereby allow the unencumbered placement of the higher row         of bricks.

The second row of bricks can then be placed. As shown in FIG. 14, the bricks of that second row are turned opposite the bricks of the first row, so as to arrange the bricks in staggered rows from one row to the next. Owing to the cutout 55 made in the upper surface 24 of the stiffeners 15 of the first row, each stiffener 15 of the second row can fit without obstacle, straddling the stiffener 15 of the first row and the adjacent base brick 1, on the side of its rear surface 12. As for the first row, the second row (and subsequent rows) is placed dry, without mortar joints, by simple fitting of the bricks of the second row into one another and into the bricks of the first row. In light of the identical quoted values (in terms of projection and width) of the grooves and the tongues, there is no functional play in the fittings, which does not hinder the placement due to the relative elasticity of the hemp concrete. The lack of joints has three advantages:

-   -   the placement time is considerably reduced as a result;     -   a large quantity of material (water, cement, aggregate) is         saved, benefiting the costs of the construction and its         environmental qualities;     -   the wall thus erected has few or no thermal bridges, its thermal         and acoustic insulation capacities thus being increased.

Once the second row of bricks is placed, the same filling in and cutting out operations are carried out in the stiffeners 15 of the second row as those done in the stiffeners 15 of the first row, so as to allow the placement of the third row. The third row is then placed, the base bricks 1 and the stiffeners 15 being oriented in the same direction as those of the first row (and therefore opposite those of the second). As before, the fitting is simple, with no mortar joints.

The cells 16 of the stiffeners 15 can then be filled in using a cement concrete, thereby embedding the frameworks 52 and forming reinforced posts 53 that vertically stiffen the wall 45 and form a reveal for the window 46.

The third row delimiting a support for the window 46, no fourth row bricks are placed between the frameworks 52. However, to horizontally stiffen the frame of the window, the following operations are carried out:

-   -   a cutout 55 is made in the upper surface 24 of each stiffener         15, to extend the upper groove 9, 23 of the bricks of the third         row between the frameworks 52 on either side as far as the cells         16 (FIG. 15);     -   a horizontal metal framework 56 is placed in said groove 9, 23         and extends from one vertical framework 52 to the other (FIG.         15);     -   the groove 9, 23 is filled in using a cement concrete to embed         that the horizontal framework 56 and thereby produce a         reinforcing beam to support the window (FIG. 16).

In order to allow the stiffeners 15 of the subsequent row to be fitted, as before, cutouts 55 are made in the upper surfaces 24 of each stiffener 15. The bricks of the following row are then placed (the fourth, in the illustrated example). As shown in FIG. 16, in order to continue erecting the wall 45 with a distribution of the bricks in staggered rows, a half-stiffener 25 is fitted on the stiffener 15 of the third row turned opposite the opening 46, with its front tongue 27 turned opposite the opening 46. A base brick 1 is then horizontally fitted on the half-stiffener 25. Stiffeners 15 and half-stiffeners 25 of this row and the following rows together form a reveal for the window 46 thus delimited.

As shown on the right in FIG. 17, and on the left in an exploded view in FIG. 18, stiffeners 15 and half-stiffeners 25 are alternated in each successive row to mount the reveal for the window 46 while preserving the staggered rows. As before, cutouts are made in the upper surfaces of the stiffeners 15 and half-stiffeners 25 to allow the fitting of each higher row.

Once the reveal for the window 46 has reached the desired height (which in this case corresponds to four rows of bricks, or a height of 1200 mm), an additional row of linking bricks 32 is placed that will participate in producing a lintel for the window 46.

As shown in FIG. 18, the linking bricks 32, simply fitted together vertically in the groove 9, 27 of the bricks of the lower row, and horizontally into each other, are horizontally stiffened using a metal framework 57 lying in the central cavity 33, which is then filled in using a cement concrete that will embed the framework 57 and thereby form a lintel beam 58 for the window 46. As shown in FIG. 19, the lintel beam 58 is nevertheless hollowed out (for example using a furring that is removed once the cement has set) by a groove 59 with the dimensions (same depth, same width) of the tongues 39, so as to allow fitting of the upper row (see below).

In order to allow the passage of the vertical frameworks 52, the bottom 38 of the linking bricks 32 placed overhanging the reveal for the window 46 are also cut out with an opening 60 with a square section, said opening 60 being filled in using a cement concrete to complete the vertical reinforcing post 53 of the wall 45 (and the window 46).

As illustrated in FIG. 19, the following row is made up of linking bricks 32 vertically fitted into the grooves 9 of the base bricks 1 of the preceding row and in the groove 59 hollowed out in the lintel beam 59.

Furthermore, in order to allow the placement of the slab 47 resting on that last row of bricks 32, side walls 37 are cut out (in this case by complete leveling) on an inner side of the linking bricks 32. As shown in FIG. 19, the slab 47 comprises profiled girders 61 (for example with a T-shaped transverse section, as illustrated), one end 62 of which is placed directly on the bottom 38 of the linking bricks 32, owing to the cutout made. The girders 61 do not, however, extend as far as the side opposite side walls 37 of the linking bricks 32: they are in fact spaced to allow the placement, between the side walls 37 and the end 62 of the girders, of a metal framework 57 for reinforcing the border of the slab 47, which will subsequently be embedded in a cement concrete.

As also shown in FIG. 19, the vertical metal frameworks 52 extend as far as the slab 47, through square openings 60 cut in the bottoms 38 of the linking bricks 32 situated overhanging the reveal for the window 46 and filled in with a cement concrete completing the vertical reinforcing posts 53.

The subsequent fastening of jambs (doors, windows) is done directly in the posts, supports, reveals and lintels of the openings. To access them, one need only form mortises in the bricks to allow the passage of fastening tongues of the jambs.

FIGS. 20 and 21 show, as an illustrative example, the production of a corner wall 63 using base bricks 1, stiffeners 15 and half-stiffeners 25. Only the placement of a first and second row of bricks are illustrated, the subsequent rows being done identically alternating between the first two rows.

As previously described, the corner wall 63 rests on a base 48 provided with a groove 51 hollowed on an upper surface, and poured over a foundation (not shown) situated below the ground level of the finished terrain. The wall 63 is made up of two wall faces 64, 65 (which are arbitrarily called left face 64 and right face 65, in reference to the orientation chosen for FIG. 20) forming an angle (a right angle in the case at hand), and comprises at least one corner post 53 stiffened by a metal framework 52 vertically implanted in the base 48. In the illustrated example, two other frameworks 52 are each implanted in a base face 48, at predetermined equal distances (1800 mm) from the corner framework 52.

The first row of bricks comprises a first stiffener 15 fitted on the base in the corner of the wall 63, with the metal corner framework 52 slipped into the cell 16 of the stiffener 15. This first stiffener 15 may be oriented differently along either of the wall faces 64, 65. In the drawing of FIG. 20, we have arbitrarily chosen to orient the stiffener 15 along the left face 64.

The first row of bricks also comprises several (two in the case at hand) base bricks 1, fitted on the base 48 in each face. In the left face 64, where the corner stiffener 15 extends, the base bricks 1 are oriented toward the corner, the front tongue 7 of the base brick 1 adjacent to the corner stiffener 15 fitting into the front groove 21 thereof. As illustrated, a half-stiffener 25 is fitted on the base 48 at the framework 52 of the left face 64, which is slipped in its cell 16. The half-stiffener 25 is oriented toward the corner, such that its front tongue 27 fits into the rear groove 11 of the adjacent base bricks 1.

In the right face 65, the (two) base bricks 1 are oriented opposite the corner, the rear surface 12 of the base brick 1 adjacent to the corner stiffener 15 being pressed flat against a side surface 17 thereof. As also illustrated, a stiffener 15 is fitted on the base 48 at the framework 52 of the right face 65, which is slipped into its cell 16. The stiffener 15 is oriented toward the corner, such that the front tongue 7 of the adjacent base brick 1 fits into the front groove 21 of the stiffener 15.

As in the example described in reference to FIGS. 13 to 19, the bricks are simply fitted into the base 48 and into one another, no mortar joints being used.

Once the first row is placed, the following two preparatory operations are carried out in anticipation of the placement of the second row:

-   -   the gap 54 between the side surface 17 of the corner stiffener         15 and the rear groove 11 of the base brick 1 adjacent to the         right face 65 is preferably filled in, preferably using hemp         concrete;     -   a cutout 55 is made in the upper surface 24 of the corner         stiffener 15, on the side of the base brick 1 adjacent to the         right face 65, to extend the upper groove 9 of the base brick 1         as far as the cell 16 and thereby allow the unencumbered         placement of the second row of bricks;     -   a cutout 55 is made in the upper surface 29 of the         half-stiffener 25 of the left face 64, on the side of the         adjacent base brick 1, to extend the upper groove 9 of the base         brick 1 as far as the cell 16 and thereby allow the unencumbered         placement of the second row of bricks;     -   a cutout 55 is made in the upper surface 24 of the stiffener 15         of the right face 65, on the side of the adjacent base brick 1,         to extend the upper groove 23 of stiffener 15 as far as the cell         16 and thereby allow the unencumbered placement of the second         row of bricks.

It is then possible to place the bricks of the second row, as illustrated in FIG. 21. As shown in the figure, in that second row, the bricks are oriented opposite those of the first row. In this way, the second row comprises an angularly offset corner stiffener 15 (in this case at a right angle) relative to the corner stiffener 15 of the first row, and is fitted overlapping thereon and on the adjacent base brick 1 of the right face 65. The base bricks 1 of the right face 65 are oriented toward the corner of the wall 63, and a half-stiffener 25 is placed at the framework 52 of the right face 65, also oriented toward the corner, its front tongue 27 fitting into the rear groove 11 of the adjacent base brick 1.

Likewise, the base bricks 1 of the left face 64 of the second row are oriented opposite the corner, and a stiffener 15 is placed at the framework 52 of the left face 64, such that the front tongue 7 of the adjacent base brick 1 fits into the front groove 21 of the stiffener 15. No mortar joint is used between the bricks. As shown in FIG. 21, the cells 16 of the stiffeners 15 and half-stiffeners 25 may be filled with cement concrete for placement of the second row. This filling may nevertheless be done at a later time, after the placement of the second row or even higher rows, to form the reinforced vertical posts 53.

One can see that, irrespective of the configuration of the construction to be built, the use of the hemp bricks described above allows an easy and rapid construction, in particular owing to the absence of jointing, which allows considerable savings in terms of time and material. As an example, the construction of a traditional building with a ground surface area of 150 m², which requires approximately 1000 bricks (in all), of the various described types, may be completed (excluding light work) in one week with one single person on the worksite, i.e. time savings of more than 50% relative to the known methods, or ordinary quarry stone-based masonry, or hemp-based masonry set on a wooden frame, or hemp concrete block-based masonry jointed and placed on a wooden frame.

By using a reinforced concrete frame to produce the posts (which may also serve as a rigid frame for the openings) and slabs, the erection, from the hemp bricks described above, of a multi-floor construction does not suffer any restrictions, whereas the professional rules regarding hemp concrete constructions made traditionally on a wooden frame limit the height of the structures to two floors (ground floor with one upper four).

The combination of solid base bricks and cellular stiffener bricks for the erection of the walls limits the number of reinforcing posts and avoids the use of a frame requiring the intervention of a specialized carpenter, while the quantity of cement concrete is nevertheless limited and the environmental qualities of the construction are preserved. However, it is fully possible to consider replacing the reinforced concrete posts with wooden pillars or non-reinforced lime concrete, just as it is possible to consider replacing the support and lintel reinforcements of the openings made from reinforced concrete with wooden beams or non-reinforced lime concrete. 

1. A method for constructing a building using prefabricated bricks made from a material comprising plant fibers agglomerated using a binder, provided with grooves and tongues allowing them to be fitted together, wherein the bricks are conned through dry-joint connection.
 2. The method according to claim 1, further comprising the combined placement of solid base bricks, provided with a groove and a tongue wherein that can be joined together, and honeycomb stiffening bricks, provided with a groove wherein and a tongue, that can be joined together as well as a cell with the passage of a reinforcing post.
 3. The method according to claim 2, further comprising: producing a mortar base; placing a series of posts wherein in the base; placing stiffening bricks at the posts wherein, with insertions of said posts into the cells of the stiffening bricks; and placing base bricks between the stiffening bricks.
 4. The method according to claim 3, wherein each post comprises a metal framework embedded in concrete.
 5. The method according to claim 3, comprising an operation for placing, at a post and above a stiffening brick, a half-stiffening brick, provided with a tongue to allow it to be joint-connected on the stiffening brick and a cell for the passage of the post, and having a length equal to half the length of the stiffening brick.
 6. The method according to claim 3, further comprising: placing linking bricks comprising a tongue allowing them to be joint-connected in the grooves of other bricks, and a central cavity delimiting two side walls and a bottom; placing a metal framework in the cavity; filling in the cavity using concrete.
 7. The method according to claim 3, further comprising: placing linking bricks comprising a tongue allowing them to be joint-connected in the grooves of other bricks, and a central cavity delimiting two side walls and a bottom; cutting out side walls; placing a slab resting directly on the bottom of the linking bricks.
 8. A brick made from a material comprising plant fibers agglomerated using a binder to implement the method according to claim 1, provided with a tongue designed to be joint-connected in a groove, wherein the tab has a height whereof the ratio to an effective height or an effective width of the brick is comprised between 1/10 and 1/4.
 9. The brick according to claim 8, wherein the ratio between the height of the tongue and the effective height or the effective width of the brick is approximately 1/6.
 10. The brick according to claim 8, wherein the material is hemp concrete. 